This invention relates to spontaneous call waiting identification (SCWID) in connection with a telephone on hold.
Currently, spontaneous call waiting identification (SCWID), is provided in many telephones and adjuncts to telephones. Typically, when a central office wishes to send SCWID information to a telephone, the central office sends to the telephone a subscriber alerting signal (SAS) audibly recognized by the user and a customer premise equipment alerting signal (CAS) which is detected by a customer premise equipment alerting signal receiver at the telephone. The telephone typically responds to the customer premise equipment alerting signal by muting a receive path in the telephone while providing an acknowledgment signal in a dual-tone multi-frequency (DTMF) format and receives FSK data from the central office. Such muting protects the user's ears from the relatively loud tones of the CAS, DTMF signals and FSK signals. It is a requirement of prior art systems that the user be actively listening to signals from the central office for the subscriber alerting signal to be heard by the telephone user.
When a telephone is placed on hold, the user is often not able to hear signals transmitted by the central office and therefore, would not be able to hear subscriber alerting signals provided by the central office, until the telephone is taken off hold. Thus, in a telephone on hold, a user may not be properly informed that a call is waiting.
The present invention provides for signalling the user in response to CAS signals, while the telephone is on hold.